1. Field of the Invention
This invention relates generally to ergonomic supports for seats, especially automobile seats.
2. Related Art
A certain percentage of seats, especially automobile seats, will be subject to abusive loads in the course of their useful life. Abusive loads may be caused by light or heavy automobile accidents, misuse by the seat occupant, sudden, violent or unexpected movement by the seat occupant or the placing of overweight items on the seat. A wide variety of moveable components are installed in seats to provide ergonomic support for the occupants of those seats. By way of example, U.S. Pat. No. 6,536,840 B1 to Schuster is incorporated by reference herein. Because such ergonomic supports are typically mass produced, production costs are often controlled by manufacturers by using the least expensive, and usually therefore the lightest, component adequate to meet expected design loads, such as the ordinary weight of a seated passenger. Ergonomic supports constructed of components that are sufficiently heavy to tolerate abusive loads as well as ordinary loads are disadvantageously expensive. There is a need in the art for a system to protect the ergonomic support from damage caused by overloads while maintaining the ability to manufacture the ergonomic support from economical components.
By and large, ergonomic supports in seats move. Movement is usually achieved by an actuator such as a hand crank or an electrical motor, which is connected to the moving parts of the ergonomic support via a linkage. The linkage may be made of rigid components such as rods, spokes or hard drawn wire. More frequently, however, the linkage takes the form of a traction cable called a Bowden cable. The bowden cable is comprised of a sleeve or conduit with a wire disposed to slide axially through the sleeve. One end of the bowden cable is attached to an actuator, and the other end is attached to the ergonomic support, such as a lumbar support. The actuator moves the wire relative to the sleeve, usually by pulling the wire out from the sleeve. An example of an actuator is found in U.S. Pat. No. 5,638,722 to Klingler which is incorporated by reference herein. The relative movement of the sleeve and wire on one end obviously moves the other end of the wire relative to the other end of the sleeve. Accordingly, one part of a moving lumbar support is attached to the end of the wire, and another part of the ergonomic support's moving parts is attached to the end of the sleeve. For example, some lumbar supports are comprised of a flexible arching panel mounted on rails. The traction cable sleeve is attached to either the top or the bottom of the panel, and the wire is attached to the other end. Thus, when the actuator pulls the wire through the sleeve, the two ends of the panel are pulled together and it arches outwards towards the seat occupant, providing an arched lumbar support for the occupant.
In the case of ergonomic supports comprised of moving components that are actuated by a traction cable, the linkage of the cable components to the moving parts is likely to be damaged in the event an abusive load is placed on the components. Accordingly, there is a particular need in the art for a system capable of being assembled with a traction cable linkage that protects components from damage from abusive loads.